Network testing systems

ABSTRACT

A method of testing a digital mobile phone network such as a GPRS or 3G network comprises creating test traffic using an unmodified test mobile phone coupled to a computer, and using the computer to measure a parameter associated with the network&#39;s response to the test traffic. The measurements made by the computer are encoded into the test traffic to create a data stream within the mobile phone network comprising test traffic, measurements relating to the test traffic, and signalling relating to the test traffic, whereby this data stream can be captured at points within the network and analysed to investigate the functioning of the network dynamically as the network is exercised with the test traffic. Software and test equipment for performing the method are also described.

CLAIM OF PRIORITY

[0001] This application claims priority under 35 USC 119 from UnitedKingdom Application No. 0128168.2, filed Nov. 23, 2001.

FIELD OF THE INVENTION

[0002] This invention is concerned with methods, apparatus, and softwarefor testing mobile phone networks and is particularly suitable fortesting data transmission over so-called 2.5G and 3G mobile phonenetworks.

BACKGROUND OF THE INVENTION

[0003]FIG. 1a shows a generic structure of a conventional mobile phonenetwork such as a GSM-type mobile phone network. The network comprises aplurality of radio masts 102 serving a corresponding plurality ofnetwork cells 100. A base station (not shown in FIG. 1a) comprising aplurality of rf transmitters and receivers is colocated with each mast102 and each base station is connected to one of a plurality of basestation controllers 104. In a GSM-type network the base station isreferred to as a Base Transceiver Station (BTS). The base stations andmasts 102 provide two-way radio communication with mobile stations suchas mobile station 116 within the cells 100. This allows two-waytransmission of voice and data traffic to and from a mobile station.

[0004] The radio link between a base station and a mobile station isprimarily managed by a base station and its associated base stationcontroller. Together these handle radio channel set-up, cell-to-cellhand-overs (in the USA referred to hand-offs) and other radio resourcecontrol functions. The radio link carries both traffic, such as speechand data traffic, and control information used to dynamically controltransmit power, to allocate radio channels to mobile stations and forsignalling functions such as paging a mobile station to alert it to anincoming call.

[0005] The network has a hierarchical structure in which a plurality ofbase station controllers 104 is connected to a Mobile services SwitchingCentre (MSC) 106 for routing calls between cells served by differentbase station controllers. The MSCs 106 are in turn connected to agateway MSC (GMSC) 108, which is connected to the standard PublicSwitched Telephone Network PSTN 114. A home location register (HLR) 110and Visitor Location Register (VLR) 112 manage call routing and mobilestation roaming; other systems not shown in FIG. 1a provide functionssuch as security and authentication and billing.

[0006] The basic structure of FIG. 1a is common to all mobile phonenetworks whether or not they are based on GSM, but the nomenclature maydiffer. For example in a 3G network a Base Transceiver Station isreferred to as a Node B, and a Base Station Controller is referred to asa Radio Network Controller (RNC).

[0007] In FIG. 1a the cells 100 are shown schematically as a set ofinterlocking, non-overlapping coverage areas but in practice thecoverage of neighbouring cells will overlap, particularly at the edges.The coverage may also have gaps where none of the local base stationsprovide sufficient signal for a mobile to operate adequately. Althoughin FIG. 1a the cells have been depicted as all being roughly the samesize in practice cell size varies from several kilometres diameter downto pico cells, which are mainly indoor cells, with a diameter of lessthan 100 m. Interference between neighbouring cells is controlled by,among other things, controlling the transmission frequency and power ofthe base station and by using modelling programmes to carefully site thebase station antennas.

[0008] It will be appreciated, even from this brief discussion, thatnetwork planning and management is complex. Although modelling can be ofgreat assistance inevitably there is a heavy reliance upon practicalnetwork testing, particularly at the early stages of network design andimplementation. Once a network has been established there is acontinuing need for practical mobile phone network testing, both fortrouble-shooting complex problems, such as problems which might onlyappear in 1 in 1000 calls, and for competitive analysis, that isanalysing the performance of a competitor's mobile phone network.

[0009] At present many mobile phone network operators test theirnetworks by means of so-called drive testing. A mobile phone is loadedwith dedicated drive testing software and connected via a serial cableto a portable computer running additional drive testing software. Thisis used to control the mobile to cause calls to be established inregular patterns to test network. Special instructions may be issued tothe phone, for example to prevent hand-over, to find the edge of a cell,or the mobile may be instructed to make repeated calls in an attempt toreproduce a fault. During these test calls the portable computer gathersdiagnostic information from the phone using the serial cable and storesthis for later analysis. This diagnostic information generally includesair interface messaging sent and received by the phone in normaloperation, that is during call set-up, call clear down, hand-over andthe like. Typically a GPS receiver is also connected to the portablecomputer so that this diagnostic information can be indexed by positionand subsequently mapped.

[0010]FIG. 1b shows an example of the type of map 120 which can begenerated using such a drive testing procedure. Geographical informationsuch as road 134 is overlaid with results of individual measurements,such as measurements 136, and a desired and/or measured pattern ofnetwork cells, such as cells 122, 124, 126 and 128. Measurements 136 maybe colour coded, for example to indicate signal strength. In the map ofFIG. 1b region 132 indicates a hole in the network coverage where callscould be dropped. Region 130 indicates an area where overlappingcoverage from two different cells operating at the same frequency couldcause interference. Examples of drive testing systems are the TEMS (TestMobile System) investigation system of Ericsson and the E-7478A GPRSdrive test system of Agilent Technologies.

[0011] U.S. Pat. No. 6,266,514 (and related patent applications WO00/28755 and WO 00/28756) describes a system for monitoring a cellularnetwork without need for drive testing, by making use of data which canbe collected from mobile phone users. Events such as a qualitymeasurement dropping below a predetermined threshold are detected andthe location of the mobile station at the time is then used to constructa map, thus automatically mapping areas of poor coverage. The mobilestation position is determined by triangulation from at least three basestations. In a variant of the technique a GPS receiver is located in themobile station and a mobile position report is transmitted to the basestation as part of the network signalling (as a conventional IS136 RQLradio quality message), and thus does not interfere with the traffic.

[0012] In another system, described in WO 99/12228, a masterautomatically initiates calls to multiple automatic mobile respondersdispersed within the coverage area of a wireless mobile phone network.This provides a real time indication of the network quality. In apreferred embodiment the responders are each equipped a GPS receiverwhich provides position, and optionally time and velocity informationfor the mobile responders. The responders are self-sufficient and may beplaced in vehicles which are not dedicated to testing, such as postal orpublic transit vehicles. The matter is connected to a conventionalfixed, land telephone line. The responders check network parameters, inparticular audio quality (using 23-tone testing), and transmit theresults back to the master mobile station 116 to via the mobile phonenetwork and PSTN. The arrangement of this system simplifies testing inthat the responders are essentially self-sufficient and automatic, thusfacilitating the monitoring of a network performance over an extendedarea from a single master location.

[0013] The above prior art techniques seek to monitor a mobile phonenetwork performance solely by making measurements at one or more mobilestations. Parameters relating to a user's perception of networkperformance, such as audio quality, the number of dropped calls and thelike are measured but the detailed technical information which engineerssetting up and optimising a phone network would ideally like to haveaccess to are not available through such tests.

[0014] In a typical third generation CDMA mobile phone network there aresome 700 parameters which may be adjusted to affect the performance ofany given cell, and a further approximately 300 parameters associatedwith GPRS data transmission. As well as the problems of poor networkcoverage and interference from adjoining cells mentioned above, networkoperators also have complex heuristics for frequency planning and radioresource usage, to attempt to maximise traffic and/or revenue. Theseconsiderations are further complicated by variations in traffic loadwith time of day and other factors.

[0015] By only measuring at a mobile station the above described priorart techniques are not able to access details of the networkfunctionality and in particular they are not able to determine theresponse of the network to an individual call.

[0016] The mobile station and network function in some respects as asingle complex entity, affected by other mobile stations connected tothe network and other traffic carried by the network. It is thereforedesirable to be able to monitor the interaction of a mobile station witha network and to investigate how the network responds to attempts by themobile station to drive traffic through the network in the context ofother traffic being carried by the network. It is further desirable tobe able to monitor such interactions dynamically since traffic on adigital mobile phone network is managed dynamically on a timescale of afew milliseconds.

[0017] GSM-type digital mobile phone networks include an Operation andMaintenance Centre (OMC) which collects statistics from networkinfrastructure elements such as base stations and switches and compilesthese into a database. This provides network operators with a high levelview of the network performance which can complement the data obtainedby drive testing. Thus, for example, the OMC typically includes countersfor every dropped call split out by cell, and time. Several companies,for example ADC Telecommunications of Minneapolis, USA provide systemsfor analysis of this OMC data. However because the OMC data isaggregated into statistics it cannot provide information relating to anindividual mobile station. Data of this type such as the number ofprotocol errors of an individual mobile station, is only available at alower level within the network.

[0018] In addition to OMC data, call trace and cell trace data is alsosometimes available. This data essentially comprises a diagnostics logcontaining messaging, including air-interface messaging, relating to asingle call or cell. These logs are produced by the base stationcontrollers of some of vendor's equipment, and can be helpful intracking down specific problems with a user or a type of handset.

[0019] A third source of data relating to the operation of a mobilephone network infrastructure is provided by protocol analysers. Aprotocol analyser comprises equipment to tap a link or interface betweeninfrastructure elements (either logical or physical. Broadly speaking aprotocol analyser simply records all the data flowing on such a link oracross such an interface as “trace file”. Such trace files can containall the messaging between the two elements connected by the link beingtapped, for example all the messaging between a base station controllerand a switch. Protocol analysers are available from companies such asTektronics, Agilent and Edixia of Telecom Technologies, France, Europe.One model “Océan” available from Edixia captures data on 300 E1 (2 Mbps)connections and provides this data over an SDH (Synchronous DigitalHierarchy) link, to allow it to be transferred over a high band widthoptical network to a data store.

[0020] Referring now to FIG. 2, this shows a generic structure 200 for adigital mobile phone network, showing the type of prior art tests whichcan be carried out.

[0021] A mobile station 202 is connected to a base station 204, servingthe cell in which the mobile station is located, across an air interfaceUu 216. The base station 204 is coupled to a base station controller 206across interface Iub 218. The base station controller 206 is connectedto a voice switch 208 via interface Iuc 220, and thence to a voice phonenetwork 210. These elements correspond to the network elements shown inFIG. 1a. Successively higher nodes concentrate the traffic and omitunnecessary operational messaging, and functionality is generallydelegated so that, for example hand-overs between base stations coupledto the same BSC are not seen by higher levels.

[0022] Mobile cellular communications systems such as GPRS (GeneralPacket Radio Service) and 3G systems add packet data services to thecircuit switched voice services. Thus base station controller 206 isalso coupled to a packet switch 212 via Iup interface 222, and thence toa packet data network such as the Internet 214.

[0023] In FIG. 2 mobile station is shown connected to a laptop computer224. This in turn is coupled to a GPS receiver 226 to allow user leveldrive testing, as shown schematically by box 228. Subscriber levelprotocol tracing 230 can be performed by capturing data from Iubinterface 218 and area level protocol tracing can be performed bycapturing data from interface Iu 220, interface Iup 222, and/orinterfaces (not shown) within voice switch 208 or packet switch 212. Ata higher level Call Detail Records (CDRs) and SS7 (Signalling SystemNo.7, an international standard used for the ISDN backbone) data 234 mayalso be collected from voice switch 208 or packet switch 212 foranalysis. Vendor specific OMC data 236 provides network statistics asdescribed above. Broadly speaking data collected from elements to theright of dashed line 238 is useful for diagnostic purposes whilst datacollected from elements to the left of line 238 provides statisticalinformation on how the network is performing but does not generallyallow the reasons for a particular level of performance to be discerned.

[0024]FIG. 2 is representative of a range of digital mobile phonenetworks including so-called 2.5G networks such as GSM/GPRS and thirdgeneration mobile communications networks as encompassed by theInternational Mobile Telecommunications IMT-2000 standard (availablefrom the International Telecommunications Union, ITU at www.itu.int andhereby incorporated by reference).

[0025] Unlike GSM, third generation technology users CDMA (Code DivisionMultiple Access) rather than TDMA (Time Division Multiple Access) andthe IMT-2000 standard encompasses three modes of operation, WCDMA(wideband CDMA) Direct Spread FDD (Frequency Division Duplex) in Europeand Japan, CDMA2000 multicarrier FDD for the USA and TD-CDMA (TimeDivision Duplex CDMA) for China.

[0026] Collectively the radio access portion of a 3G network (RNCs andnode Bs) is referred to as UTRAN (Universal Terrestrial Radio AccessNetwork) and a network comprising UTRAN access networks is known as aUMTS (Universal Mobile Telecommunications System) network.

[0027] The UMTS telecommunications systems are the subject of standardsproduced by the 3 ^(rd) Generation Partnership Project (3GPP), includingTechnical Specifications 23.101, 25.410, 25.420, 25.430 and 25.931,which are hereby incorporated by reference. The GSM standard and aspectsof GPRS are defined in ETSI (European Technical Standard Institute)standards GSM 01 to 12, which are hereby incorporated by reference;details of the GPRS radio interface are described in particular in GSM03.64 and GSM 04.60. Further aspects of the GPRS service are describedin 3GPP Technical Specification 23.060 (version 4.1.0), which is alsohereby incorporated by reference, and associated quality of serviceconcepts are defined in 3G TS 23.107 (version 3.0.0) again herebyincorporated by reference.

[0028] In FIG. 2 the interfaces shown have different names dependingupon the precise form of mobile phone network. The names of theinterfaces in the different networks are shown in the following table.Type of Interface Network Iup 222 Iuc 220 Iub 218 Uu 216 GSM/GPRS Gb AAbis Um cdma2000 Iup Iuc Aquater Uu WCDMA Iup Iuc Iub Uu

[0029] Referring now to FIG. 3a, this shows details of the base stationcontroller 206 and packet switch 212 in a GSM (and/or UMTS) networksupporting GPRS functionality.

[0030] The elements labelled in FIG. 2 as base station controller 206and base station 204 make up a Base Station System (BSS) comprising aBSC (or RNC) 300 coupled via an Abis interface 308 to base station (orNode B) 204. The BSC (RNC) 300 is also coupled via an A interface 312 tovoice switch 208, and via a PCU.A disk interface 310 to a packet controlunit (PCU) 302. The PCU 302 is in turn connected, via a Gb interface 314to a Serving GPRS Support Node (SGSN) 304.

[0031] A plurality of SGSNs 304 are connected via a Gn interface 316 toa Gateway GPRS Support Node (GGSN) 306, which in turn is connected via aGi interface 318 to Internet 214. The SGSNs 304 and GGSN 306 areconnected together by means of an IP-based packet switched network, andtogether make up part of what is referred to as packet switch 212 inFIG. 2. The SGNS and GGSN functionalities (and the functionalities ofother elements within the network) may reside on a single physical nodeor on separate physical nodes of the system. In a GPRS network securityand access control functions and tracking the location of an individualmobile station are also performed by the SGSNs.

[0032]FIG. 3b shows user end equipment 320 for use with the mobile phonenetworks of FIGS. 2 and 3a. This equipment comprises a mobile station orhandset 322, in the context of data services sometimes referred to as amobile terminal (MT), incorporating a SIM (Subscriber Identity Module)card 324. Handset 322 is coupled to a personal computer 326, sometimesreferred to as Terminal Equipment (TE), by means of a serial connection328.

[0033] Once a handset has attached to a GPRS network it is effectively“always on” and user data can be transferred transparently or nontransparently between the handset and an external data network. Personalcomputer 326 communicates with handset 322 using standard AT commands asdefined, for example, in 3GPP Technical Specification 27.007, herebyincorporated by reference. Handset 322 may require a terminal adaptor,such as a GSM datacard (not shown) in FIG. 3b.

[0034] User data is transferred transparently between handset 322 and anexternal IP network such as Internet 214 by means encapsulation andtunnelling. Where a reliable data link is not required, UDP (UserDatagram Protocol, as defined in RFC 768) may be used instead oftunnelling. A packet Temporary Mobile Subscriber Identity (Packet TMSI)is allocated to each GPRS-attached handset and a packet domainsubscriber identified by an International Mobile Subscriber Identity(IMSI) is allocated a Packet Data Protocol (PDP) address, which is an IPaddress specifying a GGSN node to access, so that data from a mobilesubscriber can be “tunnelled” to the handset's point of attachment tothe network. Radio interface resources are shared dynamically betweenspeech and data as a function of service load and operator preference,as described in more detail below. The GPRS specification separates theradio sub-system from the rest of the network to allow the radio accesstechnology to be changed or upgraded.

[0035] It will be appreciated that in a network of the general typeshown in FIG. 2, as well voice and/or data traffic each interfacecarries signalling comprising control messages for managing the network.These messages fall into one of three broad categories, call controlsignalling, mobility management signalling, and radio resourcesignalling, although the information available from this signallingdepends upon the interface concerned. For example at Abis interface 308and PCU Abis interface 310 information is available relating to therelative allocation of radio resources to voice and data traffic, butsuch detailed radio resource signalling is not available at higherlevels within the network.

[0036] Referring now to FIG. 4a, this shows a system 400 for capturingand analysing data from Abis interface 308 using a protocol analyser.The same principles apply to capturing data at other interfaces withinthe network. A plurality of E1 (2.048 Mbps) or T1 (1.544 Mbps)connections 402-410 connect base station controller 300 to base station204, one E1/T1 data feed being allocated to each base stationtransceiver. Each of these data feeds is coupled to protocol analyser414, which writes the captured data into a plurality of data files 416a-c at, for example 15 minute, intervals. These data files may bephysically located within the protocol analyser 414 or at some separate,remote location. In a subsequent step a data analyser 418 reads the datain data files 416 and analyses the data for diagnostic purposes. Invariants of the technique the captured data is made available on acomputer network rather than written to files.

[0037] Each 2 Mbps E1 data feed comprises 32 time domain multiplexed 64Kbps PCM channels, each PCM channel comprising two logical trafficchannels and two logical control channels, one each way per call. Datafrom an E1 data feed is captured and streamed into the data file byprotocol analyser 414. Data analyser 418 then implements the appropriateprotocol stack for the interface from which the data has been capturedin order to convert the data to a useful form. Data analyser 418 may beconfigured to associate traffic data with signalling data for a singlevoice call so that the progress of the call, cell-to-cell hand-overs andthe like can be monitored. At a low level such as Abis interface 308information such as RF signal level measurement reports are availablewhereas data collected at a higher level interface such as the Iup or Gbinterface 314 omits such detailed operational signalling. Likewise atthe Iub/Abis interface data is available for all subscribers attached tobase station 204 but at higher level interfaces such as Iup/Gb data fora larger number of subscribers is available.

[0038] Actix Limited of London, UK has a commercial product, CallTracker(trade mark) which can be used to analyse data collected by a protocolanalyser in this way. The Actix CallTracker works by monitoring Abismessages from multiple transceivers belonging to a number of cells. Eachtransceiver can handle multiple simultaneous calls. In order to trackevery call, the CallTracker analyses all the Abis messages for callinitiation sequences, that is call set-ups, and remembers the timeslotinformation assigned to each new call. If a timeslot assigned to a callis to be changed, for example, at a handover, then the CallTrackerinterprets the contents of the resulting Abis command sequence in theexisting timeslot and uses them to link to the new timeslot that matchesthe signalling information. The CallTracker then tracks the sequence ofmessages from the old timeslot and the new timeslot to determine whetherthe handover is successful or not and updates its internal recordsaccordingly. This process repeats until the call terminates, and in thisway the CallTracker is able to determine the timeslot information foreach call and hence is able to associate each Abis message with aparticular call.

[0039] By using a GPS receiver coupled to a personal computer a set oftimed position measurements for a mobile station can be logged in a datafile. The CallTracker software is able to combine this positioninformation with data from the protocol analyser in order to generate amap showing the position dependence of call-related parameters. Howeverthere remains a need for still more detailed information, in particularrelating to the dynamic behaviour of the network, especially where thetransmission of packet switched data is concerned. This can beillustrated by considering the allocation of radio resources in aGSM-based GPRS packet data transmission network.

[0040] In a GSM-type network 124 carrier frequencies are used eachcarrying TDMA (Time Divsion Multiple Access) data. This TDMA data isarranged in burst periods of 156.25 bits each lasting 0.577 ms, eightburst periods constituting a TDMA frame (which lasts approximately 4.6ms). One physical channel comprises one burst period per TDMA frame, sothat each frame carries 8 channels. Some channels are used to carrytraffic, such as voice and data traffic, and other channels are used forsignalling or control messages, such as the broadcast control channel,the paging channel used to alert the mobile station to an incoming call,and other channels. A group of 26 frames defines a multiframe in which24 frames are allocated to traffic channels, one frame is allocated tosignalling, and one frame is unused.

[0041]FIG. 4b shows four TDMA frames 422, 424, 426 and 428 at successivetime intervals, each frame comprising 8 timeslots a to h, during each ofwhich data can either be transmitted or received. In FIG. 4b a time slotoccupied by data traffic is indicated by “D”, a time slot occupied byspeech traffic is indicated by “X”, and an unused time slot is leftblank. In GSM-GPRS rules govern which slots may be occupied by data,these rules specifying that for a given upstream/downstreamtransmit/receive data stream the slots must be contiguous and must notcross the middle point of a frame. Speech data is given priority andwhen a call initially set up speech may occupy any time slot, althoughthe network may then contrive to shuffle the time slot occupied by aspeech connection to create a desired number of data timeslots.Typically a greater data bandwidth is needed for downstream data thanfor upstream data. In the example shown in FIG. 4b initially in frame422 three timeslots, 422 a-c are occupied by downstream data and onetimeslot, 422 f is occupied by upstream data. Then, in frame 424, twovoice calls occupy timeslots 424 a and 424 c thus leaving only onedownstream timeslot for data, timeslot 424 b. In frame 426 the callpreviously occupying timeslot 424 a has been moved to 426 h, freeing uptwo contiguous timeslots for downstream data. Finally in frame 428 thespeech channel occupying timeslot 426 c has been reallocated to timeslot428 d to once again achieve three contiguous timeslots available fordownstream data, timeslots 428 a-c.

[0042] It will be appreciated that to properly understand the behaviourof a network it is desirable to be able to monitor how individualtimeslots are being allocated to data channels, in response to both thedemands made by an individual mobile station and the load imposed on thenetwork by other traffic in the same or nearby cells. A packet datatransmission has an associated quality of service (QoS) profile which isnegotiated with the network in accordance with the available GPRSresources. The network always attempts to provide adequate resources tosupport the negotiated quality of service and the data transmissionradio priority is determined based upon this. The quality of service isalso classified depending upon whether the traffic is delay sensitive(for example video) or relatively delay insensitive (for example, webbrowsing). Generally quality requirements such as delay and reliabilityonly apply to incoming traffic up to a guaranteed bit rate.

[0043] It will be understood from the foregoing discussion that animportant problem arising in the context of 2.5G and 3G mobile phonenetworks is presented by the need to be able to analyse the dynamicbehaviour of the phone network as the network is being exercised. In acircuit switched network, once a circuit has been established it isrelatively straightforward to test the characteristics of the channel bymaking measurements at one end, such as the measurements described abovewith reference to drive testing. Likewise in a circuit switched networkdata parameters such as round trip delay are meaningful and usefulinformation regarding data throughput and delay can be obtained simplyby making measurements at the mobile station end.

[0044] By contrast in a packet switched network different packets maytake different routes to their destination, and may be delayed or evenlost entirely, depending upon other traffic within the network.Moreover, because the circuit switched voice connections take priorityat the radio interface, and because radio channels may be occupied orbecome free according to whether or when other users in the cell placevoice calls, meaningful data about the network performance must takeinto account not only what is taking place at the mobile station end,but must also take account of what is taking place at other pointswithin the network. In a further complication the priority given to datatraffic depends upon the negotiated quality of service and upon theclass of traffic being sent or received. There are additionalcomplicating factors imposed by the network operators, such as data ratelimitations placed on users trying to send or receive large volumes ofdata (to stop low rate traffic being denied access) which means thatpackets are not necessarily allocated slots on a random basis.

[0045] There is therefore a need for improved systems and methods fortesting and monitoring digital mobile phone networks, and in particular2.5G and 3G networks configured for the transmission of packet data.

SUMMARY OF THE INVENTION

[0046] According to the present invention there is therefore provided amethod of testing a digital mobile phone network, the networkcomprising, a communications network infrastructure, the infrastructurehaving a plurality of elements, including a plurality of radiocommunications base stations, and having interfaces between saidelements; and a plurality of mobile communications devices for radiocommunications with said base stations, communications between a saidmobile communications devices and said base stations, and signals oninterfaces within the network infrastructure, comprising traffic andsignalling data; the method comprising, creating test traffic between atest one of said mobile communications devices and said communicationsnetwork infrastructure, measuring at least one parameter associated withsaid traffic to provide measurement data, coding said measurement datarepresenting said measured parameter into said test traffic,demultiplexing traffic and associated signalling data for said testmobile communications device from traffic and signalling data for othersof said mobile communications devices on a test interface selected fromsaid infrastructure element interfaces, decoding said measurement datafrom said demultiplexed traffic for said test mobile communicationsdevice; and combining said decoded measurement data and saiddemultiplexed signalling data for said test mobile communications deviceto determine a response of said digital mobile phone network to saidtest traffic.

[0047] By driving test traffic over the network and then measuring theperformance of the network in response to the created traffics andinserting this measurement data into the traffic stream itself, atraffic and signalling thread is created within the network which can betapped to retrieve not only the signalling information for a given testvoice or data call but also information about the performance of thenetwork in response to the test traffic as seen from the mobilesubscriber end. The type of test and/or parameters characterising thetest traffic driven onto the network can also be determined because thetype of test being run will be known or because in embodiments of themethod, parameter characterising the test are encoded within the testtraffic.

[0048] The method may involve pulling or pushing test voice or datatraffic to or from the test mobile communications device. Since the testdevice is creating the traffic, when the traffic and signalling data ismonitored within the network subscriber-end measured parameters can belinked with network behaviour. Thus the effect of the allocation ofradio resources as illustrated in FIG. 4b or, at a higher level, theloss of packets due to a buffer overflow, can be seen.

[0049] Important parameters which can be measured for data trafficinclude data throughput and data delay. Although round trip delay can bemeasured from a mobile station with a “ping” test this is not a reliableindicator of one-way throughput or delay, and is also unrepresentativeof typical traffic because of the very small data payload such afunction requires. By contrast the present method allows a realistictest of, for example, web page download, video streaming or an FTPsession or, at a lower level, TCP or UDP data transmission protocols.

[0050] The method allows information about the data being used toexercise the network and about the bit rate and time delay as seen fromthe subscriber end to be collected from traffic within the network,concurrently with network control signals. The method allows thisinformation to be collected from any point within the network at whichtraffic and signalling information relating to the test mobilecommunications device is available. At a low level such as the Abisallocation of radio resources can be tied to data throughput and delaywhilst at a higher level such as the Gb interface other parameters suchas bandwidth allocation can be monitored.

[0051] The method can be used with either voice or data test traffic butis particularly useful for testing the response of the network to ademand for packet data transmission. This is because with a circuitswitched voice call a radio time slot is always allocated to the circuitwhereas with a data call the allocation of time slots depends upondemand.

[0052] With a 3G CDMA network users other than the test deviceeffectively constitute interference to communications of the mobile testdevice with the network. Rather than monitoring the allocation oftimeslots the radio performance and characteristics of a cell may bedetermined using the method, but the same general principles apply. In aCDMA system users other than the test mobile communications deviceeffectively add background noise and CDMA systems therefore attempt tolimit the number of users of a given cell to maintain signal quality.

[0053] The signal quality thresholds for voice and data will in generalbe different and the tolerable signal to noise ratio generally dependsupon the class of data traffic and the use to which the data is beingput. For example when downloading a large file, although a relativelyslow throughput and long latency may be tolerable as compared with, forexample, video streaming, a packet failure rate of 1 in 100 may beadequate but a packet failure rate of 1 in 2 with retry-on-failure mayprevent a large file from ever being downloaded. The present methodallows a 3G network to be tested by, for example, downloading a largefile and then allows the systems performance to be monitored atdifferent levels within the network. In particular it allows the dynamicperformance of the network, as measured at the test mobilecommunications device, to be associated with the signalling to controlthe test traffic taking place at the same time. All these can be donewithin different parts of the network.

[0054] It will be appreciated that the test interface may comprise anyinterface within the digital mobile phone network at which traffic andassociated signalling data is available, and is not restricted to aninterface defined by a formal specification for the network. It willlikewise be appreciated that the test interface may be either a logicalor a physical interface. The signalling data may comprise call control,mobility management, or radio resource signalling data or other networksignalling or control data.

[0055] In a preferred embodiment the at least one measured parameter isa parameter of traffic received at the test mobile communications devicein response to test traffic transmitted from that device, although inother embodiments one or more parameters of test traffic sent fromanother mobile communications device may be measured. Preferably themeasurement is performed on traffic received from the test mobilecommunications device by, for example, a terminal connected to thedevice, rather than on raw data extracted at a low level from within themobile communications device.

[0056] The measurement data may comprise data characterising trafficrate, traffic signal to noise ratio or bit error ratio, and trafficdelay or latency; other data such as position data (derived, forexample, from a GPS receiver) may also be inserted into the traffic.Preferably the demultiplexing extracts a traffic and signalling threadfor the test mobile communications device from other traffic andsignalling data within the network, although in other embodiments thetraffic and signalling data for the test device may simply be labelledto allow it to be identified for subsequent decoding. Similarly thedecoding, in the case of data test traffic, may also simply compriselabelling the relevant data items. Once demultiplexed and decoded themeasurement data and signalling data are combined or associated in sucha way that the data can be read together, to assist in interpreting thebehaviour of the network in response to the test traffic. Thus, again,the combining may simply comprise labelling corresponding data items toallow decoded measurement data and corresponding demultiplexedsignalling data for the test device to be identified.

[0057] The method may be used with any digital mobile phone networkincluding, but not limited to, a GSM/GPRS mobile phone network (andrelated networks such as PCS-1800 and PCS-1900 networks), cdmaOne andcdma2000 networks, IS136 (digital amps), iDEN (integrated DigitalEnhanced Network) and TETRA, and WCDMA 3G networks.

[0058] The test traffic may be created by either pulling or pushing datato or from the test device, for example by requesting data from anexternal packet data network address or from another mobilecommunications device. A transparent data transmission protocol such asTCP (Transmission Control Protocol) or a non-transparent protocol suchas UDP (User Datagram Protocol) may be employed. Where datacommunications are “always on” establishing a data communicationssession (in GPRS, a Packet Data Protocol Context Request) may compriserequesting or negotiating a desired quality of service. Measurements maythen include quality of service-related parameters such as latency—thetime it takes for a packet to cross a network connection from a senderto a receiver. The measurements may comprise, for example, timemeasurements, data throughput (for example, maximum, minimum or averagebit rate) and bit error ratio (residual or other BER). Measurements mayalso be made on packets or service data units (SDUs) to determine, forexample, SDU loss probability, SDU error probability, SDU transferdelay, and SDU transfer rate. In the case of a voice mode connectionaudio parameters such as signal to noise ratio may be measured and themeasurements encoded as, for example, audio tones.

[0059] The method may further comprise inserting test characterisingdata representative of the type of test traffic into the test traffic,and then decoding this test characterising data and combining thedecoded data with the decoded measurement data and the demultiplexedsignalling data. The test characterising data may comprise one or moreof traffic type data (voice or data), traffic class such asconversational (where time relation preservation and a low deliverydelay time are important), streaming (for example video streaming, wherethe time relationship or sequence of packets is important but thedelivery time is less important), interactive (for example web browsing,where the request-response pattern and data content are important butnot the time relation between individual packets) and background (forexample e-mail download, where timing is of little importance but thedata content must be preserved). Other test characterising data maycomprise, for example file size data, the-address of the IP network withwhich communication is taking place, and time of day, week or monthdata. More precise time data, for example derived from the networkitself or from a GPS receiver, may be included with the measurement dataand may include timing data with a precision of better than 100 ms or insome circumstances better than 1 ms.

[0060] In a preferred embodiment the test mobile communications devicecomprises an unmodified consumer mobile communications device. Thisallows the network to be tested and its performance evaluated bysimulating a subscriber to the network and by measuring the response ofthe network to the test traffic under realistic conditions simulatingactual use of network.

[0061] Preferably the traffic and signalling demultiplexing comprisesrecording substantially all the traffic and signalling data at a pointwithin the network and then demultiplexing or dethreading this recordeddata to extract a single thread comprising traffic data and associatedsignalling data for the test mobile communications device. Preferablythis demultiplexed traffic and signalling data is decoded according to aprotocol stack associated with the point at which the information wascollected, that is, the relevant protocol stack is implemented inreverse to decode the captured and demultiplexed traffic and signallingdata. For this reason the method is preferably applied (but need notexclusively be applied) at an interface or reference point at whichsignals within the network are defined according to an agreed standardfor the network.

[0062] Preferably the decoded measurement data and demultiplexedsignalling data are stored in a time series database so that themeasurement data and corresponding signalling data are retrievable as atime series for ease of interpretation and graphical presentation. Wherethe test traffic comprises packet data traffic, in a preferredembodiment the method further comprises outputting a graphicalrepresentation of the combined data to provide representation of radiointerface resources and the at least one measured parameter over time.Preferably the radio interface resources are graphically displayed, forexample as a bar chart, to show what fraction of the resources aredevoted to data traffic and what fraction are devoted to voice traffic.In other embodiments, however, the graphical representation may simplyindicate a variation in the radio resources allocated to data over time.A particularly preferred embodiment displays data throughput and/ordelay parameters over time in association with the radio resources toallow a side by side comparison of network function and a measure ofperceived subscriber quality of service.

[0063] In another aspect the invention provides mobile communicationsequipment for connecting to a mobile communications device for testing adigital mobile phone network, said mobile communications equipmentcomprising a mobile communications device driver having a traffic inputfor driving traffic to said mobile communications device and a trafficoutput for outputting a traffic received from said mobile communicationsdevice; a test traffic supply to supply test traffic; a trafficparameter measurer configured to receive an input from said devicedriver traffic output and to provide traffic parameter measurement datarepresenting a measured traffic parameter; and a combiner configured tocombine said test traffic from said test traffic supply and measurementdata from said traffic parameter measurer and to provide a combinedtraffic output to said traffic input of said device driver; whereby, inoperation, the equipment outputs traffic data comprising a combinationof test traffic for testing said digital mobile phone network andtraffic parameter measurement data to said mobile communications device,said traffic parameter measurement data representing a measuredparameter of traffic received from said digital mobile phone network viasaid mobile communications device as a response to said test traffic.

[0064] The mobile communications equipment can be used with the abovedescribed method for testing a digital mobile phone network and providescorresponding advantages and benefits. In a preferred embodiment themobile communications equipment comprises a suitably programmed generalpurpose computer having a serial or other port for connecting thecomputer to a test mobile communications device. Thus the mobilecommunications device driver, test traffic supply, traffic parametermeasurer, and combiner preferably each comprise a portion of a programmecode for controlling the computer to provide the required function.Similarly the traffic input and output of elements such as the devicedriver may comprise, for example, registers or memory areas.

[0065] In a preferred embodiment the combiner interleaves themeasurement data with the test traffic to form a single output trafficstream. The test traffic may be generated randomly or loaded from a datastore, and is preferably packetised for presentation to the devicedriver. The equipment is preferably controlled by a test sequencecontroller, in a preferred embodiment comprising a state machine. Wherevoice rather than data test traffic is employed test samples may bestored as, for example, “wave” files and the measurement encoded as(digitised) audio tones.

[0066] Preferably the device driver is suitable for driving anunmodified consumer mobile communications device. In this way theequipment can be arranged to simulate a subscriber to the digital mobilephone network, preferably using realistic test traffic and theperformance of a network under these conditions can be evaluated.

[0067] The invention also provides computer readable programme code to,when running, implement the functions of the above described mobilecommunications equipment.

[0068] The invention also provides a carrier medium carrying computerreadable code for controlling a computer coupled to a mobilecommunications device to test a digital mobile phone network, the codecomprising computer code for, a mobile communications device driverhaving a traffic input for driving traffic to said mobile communicationsdevice and a traffic output for outputting a traffic received from saidmobile communications device, a test traffic supply to supply testtraffic, a traffic parameter measurer configured to receive an inputfrom said device driver traffic output and to provide traffic parametermeasurement data representing a measured traffic parameter and acombiner configured to combine said test traffic from said test trafficsupply and measurement data from said traffic parameter measurer and toprovide a combined traffic output to said traffic input of said devicedriver, whereby, in operation, the computer outputs traffic datacomprising a combination of test traffic for testing said digital mobilephone network and traffic parameter measurement data to said mobilecommunications device, said traffic parameter measurement datarepresenting a measured parameter of traffic received from said digitalmobile phone network via said mobile communication device; as a responseto said test traffic.

[0069] The carrier medium may comprise a data carrier or storage mediumsuch as a hard or floppy disk, ROM or CD-ROM, or an optical orelectrical signal carrier.

[0070] In another aspect the invention provides a method of using amobile communications device to facilitate testing of a digital mobilephone network, the method comprising, controlling said mobilecommunications device to send test traffic over said digital mobilephone network, receiving traffic from said digital mobile phone networkusing said mobile communications device, measuring at least oneparameter associated with said received traffic to provide trafficparameter measurement data; and inserting said traffic parametermeasurement data into said test traffic, to thereby facilitate testingof said digital mobile phone network.

[0071] Preferably the method further comprises providing stored orrandom test traffic data from a test traffic data supply, coding thistest traffic for transmission, coding the measurement data andinterleaving the coded test traffic and measurement data, and providingthis interleaved data to the mobile communications device driver.

[0072] The invention also provides computer readable programme code to,when running, implement this method. In a related aspect the inventionprovides test equipment for testing a digital mobile phone network, thenetwork comprising, a communications network infrastructure, theinfrastructure having a plurality of elements, including a plurality ofradio communications base stations, and having interfaces between saidelements; and a plurality of mobile communications devices for radiocommunications with said base stations, communications between a saidmobile communications devices and said base stations, and signals oninterfaces within the network infrastructure, comprising traffic andsignalling data; the test equipment comprising, an input to receive datacollected at a test one of said interfaces, said received datacomprising traffic and signalling data for mobile communications devicesusing said network, a demultiplexer to identify test traffic andassociated signalling data for a test one of said mobile communicationsdevices from said received data, a decoder to identify measurement datarepresenting at least one measured parameter associated with said testtraffic embedded in said test traffic, and a data store to store atleast said test traffic signalling data in association with saidmeasurement data in such a way that time series measurement data andcorresponding signalling data are retrievable from the data store.

[0073] This test equipment can be used for implementing the abovedescribed method of testing a digital mobile phone network, and providescorresponding advantage and benefits.

[0074] Preferably data is collected from the test interface using aprotocol analyser or similar equipment and is stored in a data store.The test equipment input may then comprise a computer network connectionto the data store, although in other embodiments data may be transferredfrom the protocol analyser data store to the test equipment on disk.

[0075] In a preferred embodiment the test equipment comprises a suitablyprogrammed general purpose computer and the demultiplexer, decoder anddata store comprise portions of programme code. Preferably thedemultiplexer and decoder separate or extract the desired data from theremainder of the data, but in other embodiments the data of interest maysimply be suitably labelled. The data store preferably comprises a timeseries data base, and preferably the equipment includes an output deviceto output a graphical representation of time series measurement data andcorresponding signalling data.

[0076] The invention also provides computer readable programme code to,when running, implement the functions of the above described testequipment.

[0077] The invention further provides a carrier medium carrying computerreadable code for controlling a computer to test a digital mobile phonenetwork, the network comprising, a communications networkinfrastructure, the infrastructure having a plurality of elements,including a plurality of radio communications base stations, and havinginterfaces between said elements, and a plurality of mobilecommunications devices for radio communications with said base stations,communications between a said mobile communications devices and saidbase stations, and signals on interfaces within the networkinfrastructure, comprising traffic and signalling data, the codecomprising computer code for providing, an input to receive datacollected at a test one of said interfaces, said received datacomprising traffic and signalling data for mobile communications devicesusing said network, a demultiplexer to identify test traffic andassociated signalling data for a test one of said mobile communicationsdevices from said received data, a decoder to identify measurement datarepresenting at least one measured parameter associated with said testtraffic embedded in said test traffic; and a data store to store atleast said test traffic signalling data in association with saidmeasurement data in such a way that time series measurement data andcorresponding signalling data are retrievable from the data store.

[0078] The carrier medium may comprise any conventional data carrier orstorage medium or an optical or electrical signal carrier.

[0079] In a corresponding aspect the invention provides a method ofprocessing data from a digital mobile phone network to facilitatetesting of the network, the network comprising, a communications networkinfrastructure, the infrastructure having a plurality of elements,including a plurality of radio communications base stations, and havinginterfaces between said elements; and a plurality of mobilecommunications devices for radio communications with said base stations,communications between a said mobile communications devices and saidbase stations, and signals on interfaces within the networkinfrastructure, comprising traffic and signalling data, the methodcomprising, inputting data from a test one of said interfaces, saidinputted data comprising traffic and signalling data for mobilecommunications devices of said plurality of mobile communicationsdevices, demultiplexing said inputted data to identify test traffic andassociated signalling data for a test one of said mobile communicationsdevices, identifying measurement data representing at least one measuredparameter associated with said test traffic embedded in said testtraffic; and storing said test traffic signalling data in associationwith said measurement data so as to be able to retrieve a time series ofmeasurement data and the corresponding test traffic signalling data.

[0080] The invention also provides a system for testing a digital mobilephone network comprising a combination of the mobile communicationsequipment for connecting to a mobile communications device for testing adigital mobile phone network and the above described test equipment fortesting a digital mobile phone network.

[0081] In a further aspect the invention provides a carrier mediumcarrying computer readable code for testing the performance of a mobilecommunications system as perceived by a subscriber to the system using asubscriber mobile communications device, the computer readable codecomprising code for running on a computer system coupled to saidsubscriber mobile communications device, said code being for controllingthe computer system to, send traffic over said mobile communicationssystem using said subscriber mobile communications device, said trafficincluding test traffic and coded information; and to code said codedinformation to allow said information to be identified within saidtraffic and extracted from said traffic; and wherein said informationcomprises information relating to a test activity performed by saidcomputer system.

[0082] In another aspect the invention provides a carrier mediumcarrying computer readable code for analysing the performance of amobile packet data communications system, the mobile packet datacommunications system including a plurality of base stations for radiocommunication with a plurality of mobile communications system devices,the system being logically divided into portions linked at interfaces atwhich measurements may be made; the computer readable code comprisingcode to, when running, analyse data captured at a said interface, saidcode being configured to control a computer system to, read datacaptured at a said interface, extract traffic data and associated mobilecommunications system operation information for one of saidcommunications devices from said read data, decode coded informationfrom said traffic data, and output a linked combination of said decodedinformation and said mobile communications system operation informationassociated with said traffic from which said information was decoded.

[0083] The decoded information and system operation may be linked bytime, for example entries being made in a database at regular intervals,each entry having a defined time, or in some other way, for example aslinked lists. The functional requirement is that the decoded informationcan be linked to the system operation information associated with orcorresponding to the traffic from which the information was decoded.This permits the two sets of data to be matched for example at timeswhich correspond to within a predetermined degree of accuracy.

[0084] Preferably the code is further configured to control the computersystem to provide a graphical representation of the decoded informationand the mobile communications system operation information associatedwith the traffic from which the information was decoded.

[0085] In a further aspect the invention provides a method [as claim59]. Preferably the method includes outputting a graphic representationof both the decoded information and the system operation informationassociated with the traffic from which the information was decoded.

[0086] The invention may be embodied in computer programme code providedto a computer by a conventional carrier medium or by a communicationsnetwork such as the Internet. As is well know to those skilled in theart, such programme code may be implemented on a single computer or in aclient-server system on one or more computers. The computer programmecode may be implemented as a single programme or as a number of separateapplications.

BRIEF DESCRIPTION OF THE DRAWINGS

[0087] These and other aspects of the present invention will now befurther described, by way of example only, with reference to theaccompanying figures in which:

[0088]FIGS. 1a and 1 b show, respectively, a generic structure of aconventional mobile phone network, and an example of a map generated bydrive testing;

[0089]FIG. 2 shows a generic structure for a digital mobile phonenetwork illustrating prior art test data sources;

[0090]FIGS. 3a and 3 b show, respectively, details of a mobile phonenetwork supporting GPRS functionality, and user end equipment for adigital mobile phone network;

[0091]FIGS. 4a and 4 b show, respectively, digital mobile phone networktesting using a protocol analyser according to the prior art, anddynamic reallocation of packet data traffic time slots in a GSM-GPRSmobile phone network;

[0092]FIG. 5 shows, conceptually, digital mobile phone network testingaccording to the present invention;

[0093]FIG. 6 shows user end equipment for testing a digital mobile phonenetwork with voice traffic;

[0094]FIG. 7 shows user end equipment for testing a digital mobile phonenetwork with data traffic;

[0095]FIG. 8 shows test equipment for decoding test traffic created bythe user end equipment of FIG. 6 or 7;

[0096]FIG. 9 shows a general purpose computer suitably for implementingdigital mobile phone test equipment software; and

[0097]FIG. 10 shows an exemplary graphical output from the testequipment of FIG. 8.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0098] Referring now to FIG. 5, this conceptually illustrates a methodof the present invention. A mobile station or handset 502 is in two-wayradio communication with a base station 504, which in turn communicateswith and is controlled by a base station controller 506 across an Iubinterface. A protocol analyser 512 is coupled to the Iub interfaceconnection between base station 504 and base station controller 506, andis thus able to capture all the signals flowing between the base stationand the base station controller and to record these in a series of datafiles 514 spaced at, for example, 15 minute intervals.

[0099] A terminal 508, such as a laptop computer, is connected to mobilestation 502 for sending and receiving commands and data to and from themobile station and thence to another device (not shown). This furtherdevice may be another mobile communications device on the same oranother network or it may be a device connected to an external networksuch as the Internet. Optionally a GPS receiver 510 is also connected toterminal 508 to provide information on the position of mobile station502 which can be used in later analysis.

[0100] The combination of terminal 508 and mobile handset 502 simulatesa subscriber using a standard mobile phone to make voice or data callsover the mobile phone network. Terminal 508 generates calls and createstest voice or data traffic, such as traffic sequences 520 and 516, inwhich is embedded measurement data or statistics and other informationsuch as GPS position information. The test traffic may be sent to orreceived from the further device by the terminal 508. The statisticalinformation, measurements, GPS locations and other data are not storedlocally but instead are incorporated within the traffic and sent throughthe network. The statistical information and/or measurements may includeone or more of data throughput rates and voice quality measures.

[0101] The embedded information is encoded to allow it to be identifiedfrom among the remaining traffic data. The embedded information may beencoded by, for example, tagging the information with unique coding keysor with keys which are expected to occur only rarely within the testtraffic. In the case of data traffic the information may be embeddedinto IP data packets; in the case of voice traffic the information isencoded into the voice channel using a channel coding scheme.

[0102] As illustrated in FIG. 5 a test data traffic stream 516 comprisesa plurality of data segments 516 a-c, 516 f into which are interleavedGPS position information 516 d and statistical information 516 e derivedfrom measurements made by terminal 508 on the test traffic. Similarly inthe case of voice test traffic 520, voice segments 520 a-c, 520 f areinterleaved with GPS segments 520 d and statistics segments 520 e.

[0103] A protocol analyser 512 or similar equipment is used to recordall of the messaging, both traffic and signalling, at a test interface.In FIG. 5, the Iub interface is illustratively shown as the testinterface but other interfaces such as Iup and Iuc could also be used.The recorded messaging contains messaging for mobile phones served bythe relevant portion of the network, and in the case of a tap on the Iubinterface as shown this information comprises messaging, including airinterface messaging, for all the mobile phones attached to the cellserved by base station 504 (assuming that all the Iub links for thatcell are tapped).

[0104] Data processing software is used to process the data files 514collected by protocol analyser 512, to demultiplex the traffic andsignalling streams for mobile station 512 and terminal 508 from theremainder of the recorded data. The demultiplexed traffic streams suchas data traffic stream 518 and voice traffic stream 522 correspond tothe traffic streams 516 and 520 sent by terminal 508 and handset 502.The traffic for the test mobile station 502 thus contains thestatistical 518 e, 522 e and other data 518 a to d, 518 f, 522 a-d, 522f, embedded into the traffic by terminal 508. The data processingsoftware extracts the statistics and other data from the recordedtraffic data streams by recognising the keys used to tag this data, andthis information is combined with network performance information whichis extracted from signalling on the same link. This combined informationmay then be used for diagnosing faults, network optimisation and thelike.

[0105] The statistical information embedded into the traffic maycomprise a statistical evaluation of measured test trafficcharacteristics, such as data throughput or latency averaged over a timeperiod. Additionally or alternatively the embedded information maycomprise individual measurements. The statistics may be interpreteddifferently depending upon the test application, and may take intoaccount factors such as the potential need to sequence out-of-orderpackets. Inserting statistical data into the test traffic not onlyallows the performance to be measured but also permits an engineer tofind out why the performance is as it is.

[0106]FIG. 6 shows user end equipment 600 for voice traffic testing of adigital mobile phone network. The equipment comprises a mobile station602 coupled to a general purpose computer 604 running softwarecomponents to provide the illustrated functions. A data store 606 storesaudio test traffic files in, for example, .wav format. Data store 606 iscoupled to a coder 608 which reads data from the data store and providesa digitised audio output 626 to a software switch 610, and thence to avoice phone device driver 612. The device driver 612 interfaces (via aphysical serial port) to mobile station 602 to provide MS 602 withdigitised audio signals and to control MS 602 to make calls. Devicedriver 612 also receives digitised audio data received over the digitalmobile phone network back from MS 602 and provides this data as anoutput to a decoder 618, which converts the data to a suitable form forcomparison with the stored test audio data.

[0107] Sometimes, depending upon the level support of the mobile stationfor ISDN, a digital audio connection is not available. In this case theuser end equipment may include a digital-to-analogue converter, forexample on a sound card, for driving mobile station 602 with analogueaudio signals. Typically a mobile phone will provide an interface for ahands-free kit which can be used for this purpose.

[0108] Comparator code 620 compares the output of decoder 618 with thestored audio data in store 606 and provides an output indicative of thedegree of similarity of the two signals and/or signal-to-noise ratio orother audio quality data. The output of comparator code 620 is processby a second coder 622 which provides a coded output 624 to another“terminal” of software switch 610.

[0109] The comparator 620 may employ any one of a number of publishedalgorithms for the evaluation of audio samples. Such speech qualityalgorithms generally compare a measured speech sample with an originalversion of the speech and provide a score; one such algorithm is ITU-TP.861, also known as PSQM (perceptual speech quality metric). Apreferred algorithm is the PAMS algorithm planned for ITU-T P.862,available from Psytechnics of Ipswich, UK which compares reference anddegraded signals and returns quality scores from 1 to 5 on two scales,listening quality and listening effort.

[0110] Coder 622 encodes measurement/statistical data output fromcomparator 620 using a channel coding scheme, in a preferred embodimentessentially frequency shift keying based upon a knowledge of the voicecoder in use in MS 602 and, optionally, in other parts of the network.For example in a GSM network voice coding is performed using a RegularPulse Excited-Linear Predictive Coder (RPE-LPC) in which frequenciesnear pre-determined key tone frequencies are transmitted only slightlychanged. For example, a 300 hertz tone might be received as a 347 hertztone with 2 dB attenuation. Preferably one, two or more of such tonesare identified and used to encode data “1”s and “0”s. In practice thevolume of statistical/measurement data sent is low—for example, 20 to 30bits may be sent over a period of 1 sec—and it has been discovered thatwhen operating at speeds of less than 100 bps conventional frequencyshift keying can be used successfully encode the embedded data.

[0111] The software switch 610 interleaves test data 626 and encodedmeasurement data 624 in accordance with a control signal 628 provided bya state machine 616. The state machine 616 is itself controlled byautocaller code 614 which controls phone device driver 612 to control MS602 to make (and/or receive) voice calls.

[0112] The voice calls may either be made between two mobile stationseach connected to user end equipment as shown in FIG. 6, one acting as amaster, the other as a slave, or voice calls may be made to or from aserver. In this latter case similar functionality may be provided bymeans of a voice card, for example from Dialogic of Parsippany, MJ, USA,installed in the server with an interface using Microsoft's TAPI(telephony API). The TAPI allows a number to be dialled and provides,for example, either PCM (pulse code modulation) data bytes comprisingthe voice traffic or, with an analogue line and card, packets of waveformat data. In this way functionality equivalent to that of FIG. 6 canbe implemented on a server.

[0113] State machine 616 controls coder 608 to read data from a set oftest traffic files in data store 606, reading each test file in turn ina repeating loop. State machine 616 also provides a control output forcoder 622 and a control output 628 for software switch 610. The statemachine controls coder 608, coder 622 and switch 610 in co-ordinationsuch that when coder 622 has enough data to constitute a segment of thetest traffic switch 610 is thrown so that device driver 612 receivesdata 624 from coder 622 rather than test traffic 626 from coder 608.Once the statistical or measurement data from coder 622 has been passedto voice phone device driver 612 the switch 610 is returned to itsoriginal position again output traffic from coder 608. In this way testtraffic and statistical/measurement data are interleaved, typically in aratio of 5:1 to 100:1, preferably in a ratio in the region of 20:1.Graphical user interface code 630 is also provided to allow a testequipment operator to select test parameters such as atraffic/measurement interleaver ratio, an FSK (Frequency Shift Keying)encoding method/audio codec employed, and/or a sequence of one or moretest files to employ.

[0114]FIG. 7 shows user end equipment 700 similar to that shown in FIG.6, for testing a digital mobile phone network using packet data testtraffic. As described with reference to FIG. 6, the equipment comprisesa mobile station 702 coupled to a suitably programmed general purposecomputer 704 running software to provide the functions illustrated bythe functional blocks within dashed line 704.

[0115] A data generator 706 generates test traffic, which may berandomly generated traffic, but which preferably comprises data from oneor more test data files. These test data files may comprise data to betransmitted over the network or they may comprise instructions, forexample to download data from a website or to set up a video phone callor to send or receive TCP, UDP, or other data packets.

[0116] Data from data generator 706 is processed by packetiser and ratecontroller code 708 to generate TCP, UDP or other protocol data packetson output 724 and, similarly to the arrangement in FIG. 6, these packetsare passed via a software switch 710 to a data phone device driver 712.Data phone device driver 712 sends and receives data and commands to andfrom MS 702, in a GPRS or 3G network using a standard set of ATcommands. Data received by MS 702 and passed to device driver 712 isdepacketised by code block 716 and processed by code block 718. In theillustrated embodiment code block 718 comprises a bit or packet ratecounter and a bit or packet error counter, although other dataprocessing functions may be additionally or alternatively be employed. Abit or packet error counter may be employed with a non-transparentprotocol such as UDP. Optionally processing code 718 may also outputinformation about the data from data generator 706 being used toexercise the mobile phone network. The raw measurements, or statisticscompiled from the raw measurements, are provided to a coder/packetiser720 which has an output 722 to switch 710.

[0117] Coder/packetiser 720 also adds a tag data sequence to thepacketised measurement and other data to allow this data to be retrievedfrom the test traffic. The tag data sequence is selected to be one whichis known not to occur in the test traffic or, where the test trafficcomposition is not known because, for example, it comprises datadownloaded from the website, the tag data sequence is selected to be onewhich is very unlikely to occur by chance within the test traffic. Forexample a repeated “101010 . . . ” pattern may be used, with a sequencelength of more than 30, and preferably more than 100 bits.

[0118] As with the arrangement of FIG. 6, a state machine 714 controlspacketiser and rate controller 708, coder/packetiser 720, and switch 710in co-ordination to interleave measurement data with the test datatraffic. The state machine 714 controls the test sequence (and may alsocontrol data generator 706), as well as test traffic parameters such asblock length and data rate. State machine 714 may also interface todevice driver 712 in order that the data rate can be controlled to beless than, equal to, or greater than a maximum data rate allowed for apacket data session over the mobile phone network. Since MS 702 iseffectively in an “always on” state for data traffic once it hasattached to the mobile phone network there is no need for an autocaller.As with the voice test traffic system of FIG. 6, however, a graphicaluser interface 728 is provided to control the data generator 706 andstate machine 714 to set the required type of test, to select orprogramme a test sequence, to enter test data and/or instructions,and/or to set other test parameters.

[0119] In the arrangements of both FIGS. 6 and 7 a GPS device drivercode portion (not shown) may be employed to interface with a GPSreceiver to provide GPS position data. This is encoded and embedded intothe test traffic, by coder 622 or coder 720 respectively, in a similarway to the measurement/statistical data.

[0120] Referring now to FIG. 8, this shows test equipment for decodingtest traffic 800 created by the subscriber end equipment of FIG. 6 orFIG. 7. A protocol analyser 802 captures data from an interface,reference point, or other point within a digital mobile phone networkand writes the captured data into a set of data files 804 a-c, in asimilar way to the prior art method described with reference to FIG. 4a.The data files 804 may be accessed directly via a computer network orindirectly by copying the data into a removal storage medium for laterprocessing and analysis.

[0121] Data from one or more data feeds tapped by protocol analyser 802is demultiplexed by data feed demultiplexer 806 and passed to a protocolstack decoder/demultiplexer 808 which extracts messaging, comprisingvoice/data test traffic and associated signalling, for a test devicesuch as MS 602, 702 of FIG. 6 or 7 from the remainder of the captureddata. At the Abis interface this can be performed by the conventionalCallTracker software available from Actix Limited, which analyses allthe Abis messages for call initiation sequences. The phone number ofMS602, 702, in a GSM network the IMSI (International Mobile SubscriberIdentity), is known and this can be used to identify call initiationfrom or to the test mobile device. Once call initiation from the mobilehas been detected the time slot information allocated to the call islogged and hand over and other time slot control messages areinterpreted using a protocol stack decoder to track the time slotallocated to the call and hence thread together test traffic andsignalling data associated with the call. The techniques applied atother interfaces within the system correspond although extracting thedata is simplified at the higher levels because time slot and radioresource allocation is generally omitted.

[0122] In the case of a data call a packet domain subscriber identifiedby an IMSI has one or more associated PDP (Packet Data Protocol)addresses either temporarily or permanently associated with it. Theseaddresses are either IP version 4 addresses or IP version 6 addresses,and are activated and deactivated through mobility management proceduresaccording to PDP context activation procedures described in, forexample, the 3GPP technical specification 23.060.

[0123] In a GPRS packet data network user data is transferred betweenthe MS and an external data network by means of encapsulation andtunnelling, in which data packets are equipped withpacket-switched-specific protocol information and transferred betweenthe MS and the GGSN. Packets are transferred between the MS and SGSNeither using SNDCP (Sub-network Dependent Convergence Protocol), or in3G networks, GTPU (GPRS Tunnelling Protocol for User Plane) and PDCP(Packet Data Convergence Protocol). Between the SGSN and the GGSNpackets are transferred using UDP-IP protocols, through tunnelsidentified by a TEID (Tunnel End Point Identifier) and a GSN (GPRSSupport Node) address. A Network Layer Service Access Point Identifier(NSAPI) is used in conjunction with the ISMI to assign a Tunnel EndPoint Identifier (TEID).

[0124] The NSAPI is used in association with a Temporary Logical LinkIdentity (TLLI) for network layer routing, and an NSAPI/TLLI pair isunambiguous within a routing area. The TLLI (Temporary Logical LinkIdentity) identifies a GSM user but the relationship between the TLLIand IMSI is known only in the MS and in the SGSN, to preserve useridentity confidentiality (this applies in a GSM-type network; similarconsiderations apply in a UMTS based network). However the TLLI can becaptured by programme code (not shown) running on the computer 604 ofFIG. 6 or computer 704 of FIG. 7, and this can be provided to protocolstack decoder/demultiplexer 808 to extract the packet data traffic forthe test mobile communications device. Since this information isavailable once the MS has attached to the network. The information maybe provided before the test sequence begins, to allow for real timedecoding and analysis of the captured test traffic and associatedsignalling. This allows packets of a session to be tracked and pulledtogether.

[0125] In an alternative approach a characteristic data pattern isinserted into one or more data packets sent from the mobile station, toallow at least one packet sent from the MS to be picked out or at leastprovisionally selected as a candidate data packet from the MS. Such afingerprint bit pattern preferably comprises a sequence of bits, forexample a random or pseudo-random bit sequence. The bit sequence ispreferably long enough to make it unlikely that the sequence will occurby chance within the intercepted data; preferably the sequence comprisesat least four bytes, and more preferably more than ten bytes. In oneembodiment a sequence of 24 bytes is employed. In practice the length ofthe sequence is limited by the length of a packet, and this can be up to1500 bytes for an IP packet, although normally packets are split downinto shorter lengths for transmission using a mobile phone network. Themaximum packet length is generally operator dependent but is normallyample for inserting such characteristic data into a packet.

[0126] Once a candidate packet has been identified from amongst thecaptured data the TLLI for the packet can be read and all thecorresponding (either later and/or earlier) packets with that TLLI canthen also be selected to reconstruct a datastream. Where a relativelyshort fingerprint bit pattern is employed there is a possibility that anincorrect datastream will have been picked out due to the chanceoccurrence of the fingerprint bit pattern in data from a mobile stationother than that which is exercising the network and measuring itscharacteristics. However the question of whether or not the correctdatastream has been identified can be resolved by attempting to decodeencoded measurement data from within the data packets since, if thewrong datastream has been identified, this will not be successful.

[0127] Use of a fingerprint test pattern or characteristic data toidentify the datastream of interest is generally the preferred method ofpicking out the data relating to the test MS as in this case all therelevant information can be derived from data tapped from an interfacewithin the network. It will be appreciated that the fingerprint patternneed only be inserted into one IP packet of a session since once thispacket has been identified the rest of the session can be extracted bythreading along the TLLI.

[0128] In the case of a UMTS-type network a Radio Network TemporaryIdentity (RNTI) performs a similar role to the TLLI and identifies aUMTS user. The relationship between the RMTI and the IMSI is known inthe MS and in the UTRAN (Universal Terrestrial Radio Access Network) andmay therefore be furnished to the decoder/demultiplexer 808 in a similarway to the TLLI. A P-TMSI (Packet Temporary Mobile Subscriber Identity)identifies the UMTS user between the MS and the SGSN and, again, therelationship between the T-TMSI and the IMSI is known in the MS and theSGSN. From the foregoing discussion it will be appreciated thatsufficient information is available to the protocol stackdecoder/demultiplexer to extract the test traffic data packets andassociated signalling from the data files 804 captured and recorded bythe protocol analyser 802.

[0129] The demultiplexed or “dethreaded” test traffic and signallingdata from decoder/demultiplexer 808 relating to the test MS and itsdriver terminal is stored in a time series database 810. At a latertime, or substantially concurrently, a data decoder/resequencer codeportion 812 operates on the data stored in time series database 810 toextract the statistics or other measurement data, and optional GPRSposition data, from the test traffic and resequences this dataalong-side the test traffic and associated signalling data. Graphicaluser interface 814 provides a plurality of user display options for thedata in time series database 810. These options may include a simplelist of the test traffic, associated network signalling and control dataand statistics/measurement/position data in a time-ordered sequence, aswell as one or more graphical presentations of the data.

[0130] It will be appreciated that the functional blocks 806, 808, 810,812, and 814 of FIG. 8 preferably comprise portions of programme coderunning on a general purpose computer such as a laptop computer. Themain components of exemplary general purpose computer 900 which may beemployed for such a purpose are shown in FIG. 9. In FIG. 9 the computeris shown having programme code elements corresponding to the data testtraffic user equipment of FIG. 7, but code to implement the userequipment of FIGS. 6 and 8 can be implemented on a similar generalpurpose computer in a corresponding manner.

[0131] The computer 900 of FIG. 9 comprises a data and address bus 902to which are connected a serial interface 904 for interfacing to amobile station such as mobile station 702 of FIG. 7, a pointing device906 such as a mouse, a keyboard 908, and a display 910. Permanentprogramme memory 918 provides local data storage for programme code forcontrolling the computer to perform the desired functions. In theembodiment of FIG. 9, the programme code comprises data generator code,packetiser and rate controller code, software switch code, device drivercode, state machine code, depacketiser code, rate/error counter code,coder/packetiser code, and graphical user interface code. Permanent datamemory 916 stores test data files comprising test traffic data. Thepermanent programme memory 918 and permanent data memory 916 maycomprise non-volatile storage such as a hard disk. Some or all of thecontents of the permanent programme memory and permanent data memory mayalso be provided on portable storage media such as floppy disk 920. Thecomputer also includes working memory 914, illustrated storing testdata. The permanent programme memory 918, permanent data memory 916, andworking memory 914 are all coupled to bus 902 and a processor 912 isalso coupled to bus 902 to load and implement code from the permanentprogramme memory. As illustrated processor 912 implements the code toprovide a data generator, a packetiser and rate controller, a switch, adevice driver, a state machine, a depacketiser, a rate/error counter, acoder/packetiser, and a graphical user interface.

[0132] Referring now to FIG. 10, this shows a particularly preferredgraphical presentation of the data in the time series database 810 ofFIG. 8, provided by graphical user interface 814.

[0133] A display 1000 comprises a time axis 1002 and a radio resourcesaxis 1004 which, in a case of a GSM-type network, is graduated in(frame) timeslots. In other networks usage of radio resources may bedisplayed differently. For each of a series of consecutive andsequential times, such as times 1002 a and 1002 b, the display shows alevel of radio resources 1008 a, 1008 b allocated to data transmissionand a level of radio resources 1010 a, 1010 b used by voice calls on thesame interface.

[0134] The radio resources allocated to data packets are indicated bybars 1008, which grow upwards as more radio resources are allocated andthe resources allocated to voice users are indicated by bars 1010, whichgrow downwards from a maximum capacity level indicated by line 1006. Itwill be appreciated that when bars 1008 and 1010 meet the availableradio resources are being utilised to their maximum capacity.

[0135] Display 1000 also depicts the one or more measured parameters orstatistics extracted from the test traffic, for example a line such asline 1012 in FIG. 10. This allows a side-by-side visual comparison ofthe subscriber end measurements with the allocated data and voice radioresources, simplifying interpretation of the data and facilitatingnetwork fault diagnosis and optimisation. The display 1000 shows thenetwork's dynamic response to the test traffic, and the time intervalsat which successive radio resource allocation and measured parametersare presented may be selected according to the type of diagnosticinformation required. Thus they may range from, for example, timeintervals of the order of a burst period, frame or multiframe, that isless than 200 ms, up to time periods of the order of seconds, minutes,or even hours. The display 1000 of FIG. 10 may be presented inpseudo-real time.

[0136] It will be appreciated that the precise form of the datapresented will depend upon the interface being tapped, and the format ofFIG. 10 is particularly suitable where the Abis or PCU Abis (orcorresponding interfaces) have been tapped. It will be recognised thatfor the display format of FIG. 10 to be employed radio resourceallocation data must be available at the tapped interface.

[0137] The display format of FIG. 10 may be varied whilst retaining itsfundamental value, which arises from being able to see network radioperformance in comparison with data metrics such as data throughputand/or data delay. Thus, for example, the axis and bar-chart type formatin display 1000 are optional and a plurality of lines 1012 (or othergraphical formats) may be provided to display a plurality of measuredparameters. Other data may also be included on display 1000 such as, forexample, an indication of the negotiated quality of service for a packetdata session.

[0138] No doubt many other effective alternatives will occur to theskilled person and it will be understood that the invention is notlimited to the described embodiments and encompasses modificationsapparent to those skilled in the art lying within the spirit and scopeof the claims appended hereto.

1. A method of testing a digital mobile phone network, the networkcomprising: a communications network infrastructure, the infrastructurehaving a plurality of elements, including a plurality of radiocommunications base stations, and having interfaces between saidelements; and a plurality of mobile communications devices for radiocommunications with said base stations; communications between a saidmobile communications devices and said base stations, and signals oninterfaces within the network infrastructure, comprising traffic andsignalling data; the method comprising: creating test traffic between atest one of said mobile communications devices and said communicationsnetwork infrastructure; measuring at least one parameter associated withsaid traffic to provide measurement data; coding said measurement datarepresenting said measured parameter into said test traffic;demultiplexing traffic and associated signalling data for said testmobile communications device from traffic and signalling data for othersof said mobile communications devices on a test interface selected fromsaid infrastructure element interfaces; decoding said measurement datafrom said demultiplexed traffic for said test mobile communicationsdevice; and combining said decoded measurement data and saiddemultiplexed signalling data for said test mobile communications deviceto determine a response of said digital mobile phone network to saidtest traffic.
 2. A method as claimed in claim 1 further comprising:interleaving said measurement data with said test traffic.
 3. A methodas claimed in claim 1 wherein said creating and measuring comprise:sending test data from said test mobile communications device to saidcommunication network infrastructure; receiving response data from saidcommunications network infrastructure; and measuring at least oneparameter of said response data.
 4. A method as claimed in claim 3further comprising establishing a packet mode data communicationssession, said establishing including determining a quality of serviceprofile characterising a target quality of service for the session, saidquality of service profile comprising at least one target parameterselected from a group comprising data rate, bit error ratio, and datadelay parameters.
 5. A method as claimed in claim 3 wherein saidmeasured parameter is selected from a group comprising data rate, biterror ratio, and data delay parameters.
 6. A method as claimed in claim1 wherein said creating and measuring comprise: establishing a voicemode connection with the communication network infrastructure; sendingaudio test data from said test mobile communications device to saidcommunication network infrastructure; receiving audio response data fromsaid communications network infrastructure; and measuring at least oneparameter of said audio response data; and wherein said measurement datais inserted into said test traffic by encoding said measurement data asaudio tones.
 7. A method as claimed in claim 6 wherein said measuringcomprises comparing said received audio response data with said sentaudio test data.
 8. A method as claimed in claim 6 wherein saidestablishing of a voice mode connection comprises making an outgoingcall from said mobile communications device using said digital mobilephone network.
 9. A method as claimed in claim 1 further comprising:inserting test characterising data into said test traffic, said testtraffic characterising data characterising the type of said testtraffic; decoding said test characterising data from said demultiplexedtraffic; and combining said test characterising data with said decodedmeasurement data and said demultiplexed signalling data to determine aresponse of said mobile phone network to said test.
 10. A method asclaimed in claim 1 wherein the method comprises using an unmodifiedconsumer mobile communications device as said test mobile communicationsdevice to simulate a subscriber to the digital mobile phone network. 11.A method as claimed in claim 1 wherein said demultiplexing of saidtraffic and associated signalling data at said test interface comprises:recording substantially all the traffic and signalling data at said testinterface; and demultiplexing said recorded traffic and signalling datato extract said traffic and associated signalling data for said testmobile communications from said recorded data.
 12. A method as claimedin claim 11 wherein said demultiplexing of said traffic and associatedsignalling data at said test interface further comprises: decoding saiddemultiplexed data according to a protocol stack associated with saidtest interface.
 13. A method as claimed in claim 1 wherein saidcombining comprises recording said decoded measurement data and saiddemultiplexed signalling data in a data store in such a way that timeseries measurement data and corresponding signalling data areretrievable from the data store.
 14. A method as claimed in claim 1further comprising outputting a graphical representation of saidcombined data.
 15. A method as claimed in claim 1 wherein said testtraffic comprises packet data traffic; wherein packet data trafficcommunicated over a radio interface between a said mobile communicationsdevice and a said base station is dynamically allocated a variable levelof radio interface resources; and wherein the method further comprises:outputting a graphical representation of said combined data, saidgraphical representation providing a representation of said radiointerface resources and of said at least one measured parameter overtime to permit a comparison of said radio interface resources and saidmeasured parameter.
 16. Mobile communications equipment for connectingto a mobile communications device for testing a digital mobile phonenetwork, said mobile communications equipment comprising: a mobilecommunications device driver having a traffic input for driving trafficto said mobile communications device and a traffic output for outputtinga traffic received from said mobile communications device; a testtraffic supply to supply test traffic; a traffic parameter measurerconfigured to receive an input from said device driver traffic outputand to provide traffic parameter measurement data representing ameasured traffic parameter; and a combiner configured to combine saidtest traffic from said test traffic supply and measurement data fromsaid traffic parameter measurer and to provide a combined traffic outputto said traffic input of said device driver; whereby, in operation, theequipment outputs traffic data comprising a combination of test trafficfor testing said digital mobile phone network and traffic parametermeasurement data to said mobile communications device, said trafficparameter measurement data representing a measured parameter of trafficreceived from said digital mobile phone network via said mobilecommunications device as a response to said test traffic.
 17. Mobilecommunications equipment as claimed in claim 16 wherein said combinercomprises an interleaver for interleaving said measurement data withsaid test traffic.
 18. Mobile communications equipment as claimed inclaim 16 wherein said test traffic supply includes a data store to storesaid test traffic; and further comprising: a test sequence controllerconfigured to control said combiner and to control provision of saidstored test traffic from said test traffic supply and of saidmeasurement data from said measurer to said combiner, to control a testsequence of traffic provided to said traffic input of said mobilecommunications device driver.
 19. Mobile communications equipment asclaimed in claim 16 wherein said device driver includes a voice devicedriver, said test traffic supply includes a data store to storedigitised audio data, and said test traffic comprises audio testtraffic, and wherein said traffic parameter measurer further comprisesan encoder configured to encode said measurement data as audio tones andto provide said encoded measurement data to said combiner for combiningwith said audio data from said data store; whereby said combined trafficoutput comprises audio data.
 20. Mobile communications equipment asclaimed in claim 19 further comprising an autocaller to control saidmobile communications equipment to automatically initiate outgoing callsusing the digital mobile phone network.
 21. Mobile communicationsequipment as claimed in claim 16 wherein said device driver includes adata device driver and said test traffic comprises packetised datatraffic.
 22. Mobile communications equipment as claimed in claim 21wherein said test traffic supply and said traffic parameter measurereach have a data packetiser for supplying packetised data to said devicedriver; and further comprising: a test sequence controller configured tocontrol said traffic supply packetiser and said parameter measurerpacketiser to control a test sequence of traffic provided to said devicedriver.
 23. Mobile communications equipment as claimed in claim 21wherein said measured traffic parameter is selected from a groupcomprising data rate, bit error ratio, and data delay parameters. 24.Mobile communications equipment as claimed in claim 16 wherein saiddevice driver is suitable for driving an unmodified consumer mobilecommunications device, to simulate a subscriber to said digital mobilephone network.
 25. Mobile communications equipment as claimed in claim16 comprising a processor and an instruction store storing instructionsfor controlling the processor to provide said mobile communicationsdevice driver, said test traffic supply, said traffic parametermeasurer, and said combiner.
 26. A combination of the mobilecommunications equipment of claim 16 and said mobile communicationsdevice.
 27. Computer readable program code to, when running, implementthe functions of the mobile communications equipment of claim 16 on acomputer system.
 28. A carrier medium carrying the computer readableprogram code of claim
 27. 29. A carrier medium carrying computerreadable code for controlling a computer coupled to a mobilecommunications device to test a digital mobile phone network, the codecomprising computer code for: a mobile communications device driverhaving a traffic input for driving traffic to said mobile communicationsdevice and a traffic output for outputting a traffic received from saidmobile communications device; a test traffic supply to supply testtraffic; a traffic parameter measurer configured to receive an inputfrom said device driver traffic output and to provide traffic parametermeasurement data representing a measured traffic parameter; and acombiner configured to combine said test traffic from said test trafficsupply and measurement data from said traffic parameter measurer and toprovide a combined traffic output to said traffic input of said devicedriver; whereby, in operation, the computer outputs traffic datacomprising a combination of test traffic for testing said digital mobilephone network and traffic parameter measurement data to said mobilecommunications device, said traffic parameter measurement datarepresenting a measured parameter of traffic received from said digitalmobile phone network via said mobile communication device; as a responseto said test traffic.
 30. A method of using a mobile communicationsdevice to facilitate testing of a digital mobile phone network, themethod comprising: controlling said mobile communications device to sendtest traffic over said digital mobile phone network; receiving trafficfrom said digital mobile phone network using said mobile communicationsdevice; measuring at least one parameter associated with said receivedtraffic to provide traffic parameter measurement data; and insertingsaid traffic parameter measurement data into said test traffic, tothereby facilitate testing of said digital mobile phone network.
 31. Amethod as claimed in claim 30 further comprising: providing test trafficdata from a test traffic data supply; coding said test traffic data fortransmission over the digital mobile phone network; coding saidmeasurement data for transmission over the digital mobile phone network;interleaving said coded test traffic and measurement data; and providingsaid interleaved data to a mobile communications device driver forcontrolling said mobile communications device to send said interleaveddata over said digital mobile phone network.
 32. A method as claimed inclaim 31 further comprising: controlling said coding of said testtraffic data, said coding of said measurement data and said interleavingusing a state machine.
 33. A method as claimed in claim 31 wherein saidtest traffic comprises audio test traffic and said coding comprisesaudio coding.
 34. A method as claimed in claim 31 wherein said testtraffic comprises packet data and said coding comprises packetizing saidtest traffic data and said measurement data.
 35. Computer readableprogram code to, when running, implement the method of claim 30 on acomputer.
 36. A carrier medium carrying the computer readable programcode of claim
 35. 37. Test equipment for testing a digital mobile phonenetwork, the network comprising: a communications networkinfrastructure, the infrastructure having a plurality of elements,including a plurality of radio communications base stations, and havinginterfaces between said elements; and a plurality of mobilecommunications devices for radio communications with said base stations;communications between a said mobile communications devices and saidbase stations, and signals on interfaces within the networkinfrastructure, comprising traffic and signalling data; the testequipment comprising: an input to receive data collected at a test oneof said interfaces, said received data comprising traffic and signallingdata for mobile communications devices using said network; ademultiplexer to identify test traffic and associated signalling datafor a test one of said mobile communications devices from said receiveddata; a decoder to identify measurement data representing at least onemeasured parameter associated with said test traffic embedded in saidtest traffic; and a data store to store at least said test trafficsignalling data in association with said measurement data in such a waythat time series measurement data and corresponding signalling data areretrievable from the data store.
 38. Test equipment as claimed in claim37 further comprising: an output device to output a graphicalrepresentation of said time series measurement data and saidcorresponding signalling data.
 39. Test equipment as claimed in claim 38wherein said test traffic comprises packet data traffic; wherein packetdata traffic communicated over a radio interface between a said mobilecommunications device and a said base station is dynamically allocated avariable level of radio interface resources; and wherein said graphicalrepresentation provides a representation of said radio interfaceresources and of said at least one measured parameter over time topermit a comparison of said radio interface resources and said measuredparameter.
 40. Test equipment as claimed in claim 37 wherein saidtraffic comprises packet data traffic and wherein said measuredparameter is selected from a group comprising data rate, bit errorratio, and data delay parameters.
 41. Test equipment as claimed in claim37 wherein said demultiplexer includes a decoder to decode a protocolstack associated with said test interface.
 42. Test equipment as claimedin claim 37 comprising a processor and an instruction store storinginstructions for controlling the processor to provide said input, saiddemultiplexer, said decoder and said data store.
 43. Computer readableprogram code to, when running, implement the functions of the testequipment of claim 37 on a computer system.
 44. A carrier mediumcarrying the computer readable program code of claim
 43. 45. A carriermedium carrying computer readable code for controlling a computer totest a digital mobile phone network, the network comprising: acommunications network infrastructure, the infrastructure having aplurality of elements, including a plurality of radio communicationsbase stations, and having interfaces between said elements; and aplurality of mobile communications devices for radio communications withsaid base stations; communications between a said mobile communicationsdevices and said base stations, and signals on interfaces within thenetwork infrastructure, comprising traffic and signalling data; the codecomprising computer code for providing: an input to receive datacollected at a test one of said interfaces, said received datacomprising traffic and signalling data for mobile communications devicesusing said network; a demultiplexer to identify test traffic andassociated signalling data for a test one of said mobile communicationsdevices from said received data; a decoder to identify measurement datarepresenting at least one measured parameter associated with said testtraffic embedded in said test traffic; and a data store to store atleast said test traffic signalling data in association with saidmeasurement data in such a way that time series measurement data andcorresponding signalling data are retrievable from the data store.
 46. Amethod of processing data from a digital mobile phone network tofacilitate testing of the network, the network comprising: acommunications network infrastructure, the infrastructure having aplurality of elements, including a plurality of radio communicationsbase stations, and having interfaces between said elements; and aplurality of mobile communications devices for radio communications withsaid base stations; communications between a said mobile communicationsdevices and said base stations, and signals on interfaces within thenetwork infrastructure, comprising traffic and signalling data, themethod comprising: inputting data from a test one of said interfaces,said inputted data comprising traffic and signalling data for mobilecommunications devices of said plurality of mobile communicationsdevices; demultiplexing said inputted data to identify test traffic andassociated signalling data for a test one of said mobile communicationsdevices; identifying measurement data representing at least one measuredparameter associated with said test traffic embedded in said testtraffic; and storing said test traffic signalling data in associationwith said measurement data so as to be able to retrieve a time series ofmeasurement data and the corresponding test traffic signalling data. 47.A method as claimed in claim 46 further comprising: outputting agraphical representation of said time series of said measurement dataand the corresponding signalling data.
 48. A method as claimed in claim47 wherein said test traffic comprises packet data traffic; whereinpacket data traffic communicated over a radio interface between a saidmobile communications device and a said base station is dynamicallyallocated a variable level of radio interface resources; and whereinsaid graphical representation provides a representation of said radiointerface resources and of said at least one measured parameter overtime to permit a comparison of said radio interface resources and saidmeasured parameter.
 49. A method as claimed in claim 46 wherein saidtraffic comprises packet data traffic and wherein said measuredparameter is selected from a group comprising data rate, bit errorratio, and data delay parameters.
 50. A method as claimed in claim 46wherein said demultiplexing further comprises decoding a protocol stackassociated with said test interface.
 51. Computer readable program codeto, when running, implement the method of claim 46 on a computer.
 52. Acarrier medium carrying the computer readable program code of claim 51.53. A system for testing a digital mobile phone network comprising themobile communications equipment of claim 16 for testing a digital mobilephone network and test equipment; the network comprising: acommunications network infrastructure, the infrastructure having aplurality of elements, including a plurality of radio communicationsbase stations, and having interfaces between said elements; and aplurality of mobile communications devices for radio communications withsaid base stations; communications between a said mobile communicationsdevices and said base stations, and signals on interfaces within thenetwork infrastructure, comprising traffic and signalling data; the testequipment comprising: an input to receive data collected at a test oneof said interfaces, said received data comprising traffic and signallingdata for mobile communications devices using said network; ademultiplexer to identify test traffic and associated signalling datafor a test one of said mobile communications devices from said receiveddata; a decoder to identify measurement data representing at least onemeasured parameter associated with said test traffic embedded in saidtest traffic; and a data store to store at least said test trafficsignalling data in association with said measurement data in such a waythat time series measurement data and corresponding signalling data areretrievable from the data store.
 54. A carrier medium carrying computerreadable code for testing the performance of a mobile communicationssystem as perceived by a subscriber to the system using a subscribermobile communications device, the computer readable code comprising codefor running on a computer system coupled to said subscriber mobilecommunications device, said code being for controlling the computersystem to: send traffic over said mobile communications system usingsaid subscriber mobile communications device, said traffic includingtest traffic and coded information; and to code said coded informationto allow said information to be identified within said traffic andextracted from said traffic; and wherein said information comprisesinformation relating to a test activity performed by said computersystem.
 55. A carrier medium as claimed in claim 54 wherein said trafficcomprises data traffic and said information is selected from a groupcomprising data throughput rate, data delay and subscriber mobilecommunications device position.
 56. A carrier medium as claimed in claim54 wherein said traffic comprises voice traffic, wherein said codingcomprises encoding said information using audio tones, and wherein saidinformation is selected from a group comprising voice qualityinformation and subscriber mobile communications device position.
 57. Acarrier medium carrying computer readable code for analysing theperformance of a mobile packet data communications system, the mobilepacket data communications system including a plurality of base stationsfor radio communication with a plurality of mobile communications systemdevices, the system being logically divided into portions linked atinterfaces at which measurements may be made; the computer readable codecomprising code to, when running, analyse data captured at a saidinterface, said code being configured to control a computer system to:read data captured at a said interface; extract traffic data andassociated mobile communications system operation information for one ofsaid communications devices from said read data; decode codedinformation from said traffic data; and output a linked combination ofsaid decoded information and said mobile communications system operationinformation associated with said traffic from which said information wasdecoded.
 58. A carrier medium as claimed in claim 57 wherein said codeis further configured to control said computer system to provide agraphical representation of said decoded information and said mobilecommunications system operation information associated with said trafficfrom which said information was decoded.
 59. A method of testing theperformance of a mobile communications system as perceived by asubscriber to the system using a subscriber mobile communicationsdevice, the mobile communications system including a plurality of basestations for radio communication with a plurality of mobilecommunications system devices, the system being logically divided intoportions linked at interfaces at which measurements may be made; themethod comprising: sending traffic over said mobile communicationssystem using said subscriber mobile communications device, said trafficincluding test traffic and coded information, said coded informationbeing coded to allow said information to be identified within saidtraffic and extracted from said traffic, said information comprisinginformation relating to a test activity performed by said computersystem; capturing data at a said interface; extracting traffic data andassociated mobile communications system operation information for one ofsaid communications devices from said captured data; decoding said codedinformation from said traffic data; and outputting a linked combinationof said decoded information and said mobile communications systemoperation information associated with said traffic from which saidinformation was decoded.
 60. A method as claimed in claim 59 whereinsaid outputting comprises outputting a graphical representation of saiddecoded information and said mobile communications system operationinformation associated with said traffic from which said information wasdecoded.